1, 2 and 3 Digit Codes: 18

CODE NUMBER
Scan tool: 18
General scan tool: P0725

CODE NAME
Engine speed sensor circuit

CODE DESCRIPTION
Technical Description
The TCM uses a crankshaft position sensor signal to calculate engine speed (which could be zero when the ignition key is in the "run" position and the engine is not running). When the calculated engine speed is almost zero, it is compared to the speed received from the Powertrain Control Module (PCM) over the CCD bus to confirm that the engine is actually not running.

Check Area
The following conditions must be met for a successful OBDII trip:
- The engine must run for more than two minutes
- The turbine speed must be greater than 600 r/min or the output speed must be greater than 400 r/min
- If the transmission is below normal operating temperature, all forward gears must be applied for 3.5 seconds each and the transmission must be in either"park" or "neutral" for 3.5 seconds.
If the transmission is hot, all forward gears must be applied for 1.5 seconds each and the transmission must be in either "park" or"neutral" for 1.5 seconds. No MIL lamp trouble codes have occurred or recurred.

Set Conditions
This code is set when the engine speed sensed by the Transmission Control Module (TCM) is different than the engine speed reported by the PCM over the CCD.

Transmission Effects
Relay open limp-in mode.


PROBABLE CAUSE
- Malfunction of crankshaft position sensor
- Harness or connector between crankshaft position sensor and TCM open or short-circuited
- Malfunction of TCM
- Malfunction of PCM





DIAGNOSTIC CHART